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Your best bet , take your vehicle to a qualified repair shop . Before you want to replace the BCM . . Professional tech would check for DTC'S - diagnostic trouble code's in the BCM before replacing part's that are not needed .
No signal at signal wire on relay ???? Which circuit wire mite that be ? Hooking up a factory or professional scan tool to view input data from the switch would also be a good step .
Headlamps
The headlamps may be turned ON 2 different ways. First, when the driver places the headlamp switch in the HEADLAMP position, for normal operation. Second, with the headlamp switch placed in the AUTO position, for automatic lamp control (ALC). During ALC, the headlamps will be OFF in daylight conditions, or low beam operation in low light conditions. Battery positive voltage is supplied to the low beam relay and the high beam relay in the underhood fuse block. When low beam headlamps are requested, the body control module (BCM) supplies ground to the coil side of the low beam relay. This activates the relay and the relay supplies voltage to the left hand low beam headlamp through the LH LOW BEAM fuse and to the right hand low beam headlamp through the RH LOW BEAM fuse. Ground for the left hand low beam headlamp is provided at G101. Ground for the right hand low beam headlamp is provided at G102. When high beam headlamps are requested, the body control module (BCM) supplies ground to the coil side of the high beam relay. This activates the relay and the relay supplies voltage to the left hand high beam headlamp through the LH HIGH BEAM fuse and to the right hand high beam headlamp through the RH HIGH BEAM fuse. Ground for the left hand high beam headlamp is provided at G101. Ground for the right hand high beam headlamp is provided at G102.
Headlamps Inoperative - Low Beams
Step
Action
Yes
No
Schematic Reference: Headlights/Daytime Running Lights (DRL) Schematics
Connector End View Reference: Master Electrical Component List
1
Did you perform the Diagnostic System Check - Vehicle?
YES - Go to Step 2
NO - Go to Diagnostic System Check - Vehicle
2
Place the headlamp switch in the HEADLAMP position.
Place the headlamp dimmer switch in the LOW position.
Do the low beam headlamps illuminate?
YES - Go to Testing for Intermittent Conditions and Poor Connections
NO - Go to Step 3
3
Disconnect the turn/headlamp switch connector C2.
Connect a 15-amp fused jumper between the headlamp low beam signal circuit and a good ground.
Do the low beam headlamps illuminate?
YES - Go to Step 4
NO - Go to Step 5
4
Inspect for poor connections at the harness connector of the turn/headlamp switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?
YES - Go to Step 7
NO - Go to Step 6
5
Repair an open or high resistance in the headlamp low beam signal circuit. Refer to Circuit Testing and Wiring Repairs .
YES - Did you complete the repair?
NO - Go to Step 7
--
6
Replace the turn/headlamp switch. Refer to Turn Signal Multifunction Switch Replacement .
YES - Did you complete the replacement?
NO - Go to Step 7
--
7
Operate the system in order to verify the repair.
Did you correct the condition?
YES - System OK
No - Go to Step 2
It's more then likely the dimmer switch .
DTC B2575
Circuit Description
The body control module (BCM) turns on the LOW BEAM relay when the ambient light sensor senses a dark condition or the low beam headlamps are requested ON. Battery positive voltage is supplied to the LOW BEAM relay at all times. The BCM grounds the LOW BEAM relay control circuit in order to activate the relay.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC B2575 Headlamp Control Circuit
B2575.01
Will set if there is a short to voltage in the low beam relay control circuit.
B2575.06
Will set if there is an open or short to ground in the low beam relay control circuit.
There are low beam and high beam fuses but it could be the bulbs first go to ford owner manual.com and register for free then download your owners manual go to roadside emergencies and your fuse box diagrams and fuse values are in there and then you will know what you have to do next fuses or bulbs I'm suspicious of both bulbs going out at the same time so check the fuses first before spending $$$on bulbs it could also be a bad wire shorting to ground or a bad bulb socket
Dennis, Make sure the low beam bulbs are OK, first. if fuses and grounds OK, it will be your multi switch, which you nay be able to disassemble and clean contacts. Low Beams Not Working Resolved
I agree, first start with bulbs, and sockets...be sure to clean sockets (corrosion) spray with PB Blaster to clean as necessary...use bulb grease when re-installing...ALSO be sure not to touch finger sweat on bulbs...this always shortens the bulb life...Hope this helps.
there are fuses for each light, high and lo beam. the grounds are grounded at all times, I dont know what you mean by open seeking. its wired like every other car. Right low beam is fuse 21 Red/White wire should be hot if fuse is good. I dont know what you mean by hooking low beam connector to battery? check fuses.
you say you replaced both bulbs, you mean right and left or both the high beam and the low beam on left side?could be a bad ground for the left headlight. there should be some ground wires there near the headlight, LF corner under hood. without a wiring diagram here at home,I am not much help.
are the high beams by themselves? or part of the same bulb for the driving lights?
sounds like you might have either a bad fuse, or a bad ground of some sort... check around the engine compartment for the grounds connected to the fire wall, and the grounds going from the lights back make sure they are not rusted or broken, if the bulbs tho are a high and low beam in one, the filiment for the lows could be blown, and that would let the high beam light...high beams are on a different circuit then the lows... get a cheap multimeter and take the low bulb correction off connect the multimeter to it and then turn the lights on look to see if the meter has any voltage going to it..... remember a car runs on DC voltage.... not AC voltage.... if you dont get any voltage to thru the wires with the light switch on then it is a break in the line somewhere.... if you have voltage then it is a bad bulb.... hope this helps you out....
Daytime Running Lamps
The daytime running lamp (DRL) system is designed to turn the high beam headlamps on, with a reduced light output, and without illuminating the high beam indicator lamp in the instrument panel. You have a DRL Module.
The multifunction switch is the stalk on your column.
This is 96 F150 circuit. Don't have 94.
Symptom Chart, Headlamps
HEADLAMPS
Condition
Possible Source
Action
Headlamps Inoperative
Circuitry open/shorted.
Damaged headlamp switch.
Blown fuse.
GO to Pinpoint Test A .
Headlamps On Continuously
Circuitry open/shorted.
Damaged headlamp switch.
GO to Pinpoint Test B .
High Beams or Low Beams Inoperative
Circuitry open/shorted.
Damaged multi-function switch.
GO to Pinpoint Test C .
One High Beam or One Low Beam Headlamp Inoperative
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